1. Field of the Invention
This invention relates to a zoom lens system capable of ultra-closeup photography and which may be used with a still camera or the like.
2. Description of the Prior Art
In zoom lenses known by the tradename MACROZOOM, a portion of the magnification-changing section or of the master lens is movable independently of the zooming operation for permitting the lens system to focus an object located very close to the camera. In all these MACROZOOM lenses, the imaging magnification is at best 1/4 times. When these lenses are employed with 8mm movie cameras, the filmed images are viewed during projection in which they are enlarged 200 times or more so that imaging magnification of 1/4 times is acceptable to provide a sufficient projection effect. In the case of still cameras, however, the filmed images are not enlarged to this degree. Thus the need for increased imaging magnification is greater than the need for the ultra-closeup effect. As a result, fixed-focus lenses have been provided for enabling the imaging magnification to be increased up to the equimultiple level. However, these zoom lenses, which have been announced for use with still cameras and which are capable of both the zooming effect and ultra-closeup photography, have also been intended for use with 8mm movie cameras so that the imaging magnification of these zoom lenses has been at best 1/4 to 1/3 times, which is far inferior to the imaging magnification of lenses having a single focal length. Furthermore, these zoom lenses have disadvantages, such as the complicated and enlarged interior configuration of the lens system and the resulting increase in the weight of the lens system when the imaging magnification of these zoom lenses is increased up to an equimultiple level by the original lens systems of 8mm movie cameras.